format_g729.c

Go to the documentation of this file.

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Save to raw, headerless G729 data.
 * \note This is not an encoder/decoder. The codec for g729 is only
 * available with a commercial license from Digium, due to patent
 * restrictions. Check http://www.digium.com for information.
 * \arg Extensions: g729
 * \ingroup formats
 */

/*** MODULEINFO
 <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/mod_format.h"
#include "asterisk/module.h"
#include "asterisk/endian.h"
#include "asterisk/format_cache.h"

/* Some Ideas for this code came from makeg729e.c by Jeffrey Chilton */

/* Portions of the conversion code are by [email protected] */

#define BUF_SIZE 20 /* two G729 frames */
#define G729A_SAMPLES 160

static struct ast_frame *g729_read(struct ast_filestream *s, int *whennext)
{
 size_t res;

 /* Send a frame from the file to the appropriate channel */
 s->fr.samples = G729A_SAMPLES;
 AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
 if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
 if (res && res != 10) /* XXX what for ? */ {
 ast_log(LOG_WARNING, "Short read of %s data (expected %d bytes, read %zu): %s\n",
 ast_format_get_name(s->fr.subclass.format), s->fr.datalen, res,
 strerror(errno));
 }
 return NULL;
 }
 *whennext = s->fr.samples;
 return &s->fr;
}

static int g729_write(struct ast_filestream *fs, struct ast_frame *f)
{
 int res;

 if (f->datalen % 10) {
 ast_log(LOG_WARNING, "Invalid data length, %d, should be multiple of 10\n", f->datalen);
 return -1;
 }
 if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
 ast_log(LOG_WARNING, "Bad write (%d/10): %s\n", res, strerror(errno));
 return -1;
 }
 return 0;
}

static int g729_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
 long bytes;
 off_t min,cur,max,offset=0;
 min = 0;
 cur = ftello(fs->f);
 fseeko(fs->f, 0, SEEK_END);
 max = ftello(fs->f);

 bytes = BUF_SIZE * (sample_offset / G729A_SAMPLES);
 if (whence == SEEK_SET)
 offset = bytes;
 else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
 offset = cur + bytes;
 else if (whence == SEEK_END)
 offset = max - bytes;
 if (whence != SEEK_FORCECUR) {
 offset = (offset > max)?max:offset;
 }
 /* protect against seeking beyond begining. */
 offset = (offset < min)?min:offset;
 if (fseeko(fs->f, offset, SEEK_SET) < 0)
 return -1;
 return 0;
}

static int g729_trunc(struct ast_filestream *fs)
{
 int fd;
 off_t cur;

 if ((fd = fileno(fs->f)) < 0) {
 ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for g729 filestream %p: %s\n", fs, strerror(errno));
 return -1;
 }
 if ((cur = ftello(fs->f)) < 0) {
 ast_log(AST_LOG_WARNING, "Unable to determine current position in g729 filestream %p: %s\n", fs, strerror(errno));
 return -1;
 }
 /* Truncate file to current length */
 return ftruncate(fd, cur);
}

static off_t g729_tell(struct ast_filestream *fs)
{
 off_t offset = ftello(fs->f);
 return (offset/BUF_SIZE)*G729A_SAMPLES;
}

static struct ast_format_def g729_f = {
 .name = "g729",
 .exts = "g729",
 .write = g729_write,
 .seek = g729_seek,
 .trunc = g729_trunc,
 .tell = g729_tell,
 .read = g729_read,
 .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
};

static int load_module(void)
{
 g729_f.format = ast_format_g729;
 if (ast_format_def_register(&g729_f))
 return AST_MODULE_LOAD_DECLINE;
 return AST_MODULE_LOAD_SUCCESS;
}

static int unload_module(void)
{
 return ast_format_def_unregister(g729_f.name);
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw G.729 data",
 .support_level = AST_MODULE_SUPPORT_CORE,
 .load = load_module,
 .unload = unload_module,
 .load_pri = AST_MODPRI_APP_DEPEND
);